Jeep keeps breaking down

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calmimi's picture

Calum Faeorin-Cruich
Lake Cowichan
Jeep keeps breaking down

Hope someone can throw some light on my issue.

I have a 2014 Jeep Wrangler Sahara that every week or two just stops while driving. The engine just shuts down. If I unplug the two connectors from the electrical module at the front of the engine that looks like a silver laptop on its end, then the jeep starts as normal and I get another week or so driving.

I bought a code reader and plugged it in a few times when this happened and it showed no codes. Only one time did it show a code which was PO129. I took the jeep into Galaxy motors in Duncan who did a full diagnostic but could find nothing.

They are stumped, I'm stumped as what to do next. Anyone out there have any idea what could be causing this issue.

Cheers,

Calum

Trackick's picture

Simon
Duncan

I believe the laptop module you are referring to is the powertrain control module (PCM). Hard to know for sure unless you have a photo.

Not a mechanic myself, but maybe the connections to the PCM are getting dirt or water in them? Or rattling loose somehow over time.

The other option could be, your code PO129 is for low intake barometric pressure, could be that the MAP sensor is intermittently failing, and by unplugging power to the PCM you are effectively resetting the fault? Only to have it fault again a week later.

Again I'm no mechanic but it could be something like that. Hard to diagnose if the code comes and goes

Have you found the problem that was causing your Jeep to stall? If not, I may have a couple of ideas. Some are obvious, a couple others not as much.

calmimi's picture

Calum Faeorin-Cruich
Lake Cowichan

Hi there,

I thought I had solved the problem by re-setting the PCM. When we did that the jeep ran for almost a month before breaking down again and it broke down twice on the same day which it never has done before. Normally its a couple of weeks before breaking down. My other half read that if you have too many key on the one bunch then the downward pressure could affect the fuel pump as it somehow switches on when you insert the key so if the keys have a downward pressure then it tells the fuel pump that you have removed the keys and switches off so I have taken all my keys as the bunch was fairly heavy and just have the one key and its been about a week since it broke down so that's as far as we have gotten.

Cheers,

Calum

calmimi's picture

Calum Faeorin-Cruich
Lake Cowichan

Hi there,

Thanks for the ideas. We are still having the same issues and nobody seems to have any definite idea what is causing it. I just don't want to be driving down a steep slope in low ration for the engine to give out and the steering and brakes to go. Might think about changing the PCM altogether to see if that makes a difference.

I had a Ford truck with the same problem. Turned out it was an intermittent problem with the fuel pump. It would randomly starve the engine of fuel and it would cut out. After a few minutes of letting the truck sit and then trying to start it again, it eventually would. I talked to several mechanics who all said it could be caused be a few things (which I tried and eliminated):

1. Battery and/or alternator problem. Check all battery and alternator wires to ensure good connection. Remove negative/black wire while truck is running, if engine stalls, the problem is the alternator.
2. Engine ground. Check that the engine has a strong ground to the frame. This can cause a whole bunch of different problems andapparently stalling is one of them.
3. Bad engine sensor. This may not be your problem since I'd expect an OBD code and you mentioned you don't get any.

LIke I mentioned, my problem turned out to be the fuel pump which is the most difficult to trace and the last one I tried. Once it was replaced I never had the problem again. Hope some of this helps.

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